The present invention relates generally to optical spectrometers, and more particularly to compact optical spectrometers.
Optical spectrometers isolate individual wavelength components of light radiated from a source to measure wavelength-specific properties of the source. Scientists use optical spectrometers to analyze characteristics of various specimens, such as geological samples, biomedical samples, etc. Typically, a spectrometer includes a spatial filter, a grating, and a detector array. The spatial filter spatially filters the incident light radiated from the source, while the grating spatially shifts the direction of the spatially filtered light as a function of wavelength. In so doing, the grating directs different wavelength components of the spatially filtered light to different areas of the detector array. Detector elements in the detector array convert sensed light to an electrical output signal. Processing electronics process the output signals to generate the spectrum to quantify wavelength-specific properties of the source.
Conventional gratings accommodate a wide spectral range, and therefore, shift the various wavelength components of the spatially filtered light across a physically wide detector area. Because they use gratings that shift all of the wavelengths along a single direction, conventional spectrometers require physically wide detector arrays to accommodate the spatially wide range of dispersed light. This results in undesirably large spectrometers. Other designs, such as the spectrometer described in U.S. Pat. No. 5,559,597 to Battey et al., handle the wide range of dispersed light by folding different portions of the optical spectrum onto different non-overlapping rows of a detector array. While the Battey device reduces the width requirements for the detector array, the described solution is not ideal for all circumstances. Therefore, there remains a need for alternative spectrometers.